尾巨桉中大径材立地指数编制及施肥对立地指数的影响

Development of a Site Index for Large-diameter Timber Production with Eucalyptus urophylla × E. grandis and Effect of Fertilization on the Site Index

本文采用了连续12次16年生标准地的观测数据,以模型H=a+b/(c+A)作为导向曲线,标准年龄为7 a,编制了尾巨桉中大径材立地指数表。经过χ~2检验和标准差检验综合得出,所编制的立地指数合理,科学可行。本研究提出培育桉树中径材的立地指数不应小于20,培育桉树大径材的立地指数不应低于24。施肥提高了林地的立地指数,施肥量越多,立地指数提高的幅度越大;这种提高幅度在施肥量少的时候较大,当施肥量逐步增大的时候,立地指数的提高幅度逐渐变小。

Data from 12 consecutive observations from each of 16 sample plots were analysed using models of the form H=a＋b/（c＋A） in order to develop a Eucalyptus urophylla x E. grandis site index for larger diameter timber production, with the standard age of site index determination set at 7 years. Based on examination of the variables % and standard deviation, the site index developed in this study seems reasonable and scientific. According to the study, the requirement of site index for cultivation of medium diameter timber should not be less than 20 and the requirement of site index for cultivation of large diameter timber should not be less than 24. Fertilization was found to improve the site index of plantation land; with the more fertilizer applied, the greater the increase in the site index. This increase in site index was larger at lower rates of fertilizer application, and the increase of site index gradually decreased as the amount of applied fertilizer increased.